PROJECT SUMMARY Title: Dietary restriction promotes vascular health through hydrogen sulfide-mediated angiogenesis Aging is a prime risk factor for cardiovascular disease, neurodegenerative disease and type II diabetes, all of which involve progressive dysfunction of the vasculature, the system of blood vessels and capillaries that deliver blood throughout the body. Maintenance of vascular health is expected to have major beneficial effects on healthspan and lifespan. Angiogenesis, or the growth of new blood vessels from endothelial cells in existing vessels, is a process by which vascular health and function can be maintained or improved. Angiogenesis is triggered under normal physiological situations such as exercise, but also by pathophysiological stimuli including ischemia due to blockage of a blood vessel. In both cases, oxygen deprivation is a major trigger of angiogenesis through activation of a genetic program controlled by the hypoxia inducible factor 1 alpha (HIF1?) transcription factor. Dietary restriction, generally defined as reduced food intake without malnutrition, increases lifespan, healthspan and stress resistance in experimental organisms, but the underlying cellular and molecular mechanisms remain largely unknown, particularly in mammals. Our surprising preliminary data indicate that nutrient restriction can promote angiogenesis via a novel mechanism independent of hypoxia or HIF1 ?. Specifically, we found that restriction of just the sulfur-containing amino acids methionine and cysteine, a regimen also known as methionine restriction, strongly increased muscle capillary density in mice. This occurred through the activation of the amino acid deprivation sensor GCN2 and the downstream transcription factor ATF4. It also required another downstream ATF4 target, the transsulfuration pathway gene CGL, a major producer of endogenous hydrogen sulfide (H2S). Increased H2S was in turn required for angiogenesis through a novel mechanism involving a metabolic switch from oxidative to glycolytic metabolism. Here, we propose to test the hypothesis that dietary restriction in general, and methionine restriction in particular, increases lifespan and healthspan of rodents in part by increasing angiogenesis via a novel mechanism requiring CGL and H2S. We will test the functional consequences of increased angiogenesis in standard rodent preclinical models of vascular function/dysfunction, as well as its contribution to lifespan extension by dietary restriction. Taken together, we expect to uncover novel pathways controlling angiogenesis and vascular function with the potential to translate to humans in the context of aging and aging-related disorders.